Telephone system



April 24, 1928.

M. B. STAZAK TELEPHONE SYSTEM Filed June 18. 1926 Patented Apr. 24, 1928. i

UNITED "STATES PATENT OFFICE.

MICHAEL B. s'rn'zax, or cmcAeo n mois, nsszexoit 'ro KELLOG swrrcnnonnn &

SUPPLY 00., or c 'ncneo, I LINOIsn coRroRA'rIoN or ILLINOIS.

I rnnnrnonz sira'rmL .Ap plication filed June 18, 1926. Serial No. 116,804.

My invention relates ingeneral to telephone systems in which manual link or cord circuits are provided for interconnecting telephone lines,'and has to do more particu- 1 larly with the so called multiple answering jack systems inwhichthe answering jacks of the lines are distributed among difierent operators po.sitions, and inwhich there is a line signal for each jack at the different operators positions so that when a call is initiatedover any line the linesignals'at the operators? positions are lighted and any one of a plurality of, operators-may seize the call to the cxclusion of the other o perators'and in which instantaneous disconnect pc and, recall are' provided.

1 In cord circuits of the above characteron a revertive call in which a ;calli-ng subscriber initiates a call andwishes to converse with a subscriberonthe same line the usual procedure is for the operator to request the calling-subscriber to replace his receiver for replace their receivers upon their switch- I the more 'tullyhereinafter described in the hooks to bring about the lighting of the supervisory lamps.fShould, either of the subscribers recall they would immediately etfa'ce the supervisory signalsof the cord circuit'connected to the line and to attract the attention of the operator the receiver at also bring about the 'deenergization ofthe cut oftrelay of the connected line to. place the line relay of the line under the control of the subscribers so thatxshould either one on the party line to which the cor-dis connected recall-before the plugis withdrawn the line relay will operate to light the line signals so that the same operator; that han- After the;

clusion of the other.

- rovision of meansin the cord circuit where- 'y the line circuit of the calling subscriberis disconnected from the connected cordcircuit so that upon the removal of the receiver at the calling substation from its 'switchhook the multiple line signals associated with the calling line are lighted. and the recall may be seized by the same operator that handled the original call or by another operator,

either one to the exclusion ofthe other, ,de-

nding on which one seized the recall first.

Another feature of my invention is the" A further feature of my invention is the provisionof means in the cord circuit whererevented from by the called subscriber is initiating a recall until a ter the callin subscriber has replaced his receiver at whic time the means in the cord circuit operate line circuit so'that upon the removal of the receiver at the called substation from the switchhook the multiple line signals of the called line are lighted and the call may be answered by the operator who established following specification. I

to disconnect the connected cord fromthe For a more-complete understanding of my invention reference may be had to the accompanying drawing. To the left of the drawing I show a common battery substation A terminating atthe exchange in a'line circuit L comprising the usual line relay LR and cut 011' relay CO. I also provide a plurality of answering jacks J each having an associated line lamp S eachjack and its lamp appearing at different operators posigized upon the initiation of a call, the associated linelamps S are lighted anda-ny one of a pluralityof operators'may. seize the call to the exclusion of the others.

Itions so that when the line relay LR is ener Referring now to the cord circuit C it comprises an answering plug AP and a calling plug GP. connected by the heavily marked tip and ring conductors and having the'condensers K and K" interposed. The answering end of the cord circuit comprises a linkdisconnect-relay LD which is operated when theranswering plug is inserted into the jack of a calling line and an answer ing supervisory relay AS which is operated when therelay L1) is operated. A listening relay LS is also provided which operates to connect the operators set 0, to the cord conductors. A link dlsconnect control relay LDC, an auxiliary sleeve relay AU and a.

revertive recall control relay CR are also provided for the cord circuit C and the function of these relays will be more fully hereinafter described.

The calling end of the cord circuitC'comprises a link disconnect relay LD which is operated when the calling plug is'inserted 111150 the ack of a called line. A r1ng1ng control relay ROE is provided which is operated when a ringing key plunger of the ar't line rin ine' ke HR is de ressed to deencrgizedto connect ringing current from the selected generator of the proper frequency to intermittently actuate the call bell at the called substation. Acalling supervisory relay CS is also provided as are also "the answering and calling supervisory signals "AL and CL for the usual supervisory purposes.

To the right of the drawing I illustrate a called substation l3 terminating at the exchange in a line circuit L comprising the usual line relay LR, cut oil relay CO, multiple answering jacks J and their associated line signals S. Having described in general the arrangement of the circuits and apparatus employed in my invention, I now describe more in detail the operation of the circuit A in establishing connection between a calling and a called subscriber. Assuming that the subscriber at the substation A initiates a call the removal of the receiver at the substation closes an energizing circuitfor line relay LR of the line circuit L and the closing of its alternate contact lights the line lamps S at a plurality of operators positions. Assuming that the operator associated 'with the cord circuit C answers'the call,the insertion of theanswering plug AP into thejack J of the calling line A establishes a series energizing circuit for the out off relay C0 of the line clrcuit L and the link disconnect relay LD of the cord circuit C which is traced from battery through the low and high windings relay CO. The high resistance winding 3 of the relay L1) is shunted, thisarrangement providing for secret service as the relay L1) of a secondcord will not operate in series with the relay GO, as the-shunt of the low winding 2 of the relay LD of theafirst cord circuit renders the relay LD- of the second 7 cord inoperative so that should the'operator at any other cord attempt to seize the-call 7 after the first operator has connectedito' the calling line, the operator of the second cord is prevented from connecting with the call; ing subscriber as the shunt offthe low-winding 2 of the relay LD of the first cord circuit at s 1 prevents'the relay Ll) of the second cord 7 from operating and this prevents the operator of the second cord from being connected to the calling line.- The operator of the sec ond cord not receiving an answer from-the calling subscriber, knows that the call'has been answered" by another operator and therefore withdraws the plug of the second cord from the 'multipleanswering jack of the calling line. a

ductor 11 to ground through the upper windng f the relayAS. The closing of alternate contact 12 of the relay AS closes a circuit for the listening relay LS, traced from battery through the winding of the relay LS,conductor 13, alternate contact 12 of the relay AS, conductorll, alternate contact 15 of relay LD and conductor 16 to ground at normal contact 17 of the link disconnect relay LD associated with the calling end of the cord C. The relay LSupon energizing closes its alternate contacts 18, 19 and 20 to connect the operators set 0 to the cord conductors and the closing of its alternate contact 21 establishes a locking circuit for itself traced from battery through the winding of the relay LS, its alternate contact 21, con-' ductors 22 and 14, alternate contact 1501? re lay LD, conductor 16 to ground at normal contact 17 of relay LD. 7 1,

The operator having been connected with The relay LD upon energization closes its alternate contacts 8 and '9 to establish a-cir-.

the cord conductor-s now inquires the Wants of the callingsubscriber at substation A.

Assumingthat it isthe subscriber at; the substation B that is wanted,]the operator tests themultiple answering jack J 5 of the called line as to its idle or busy condition and if the said'line is busy the sleeve ofthe jack is of a batteryv potential different than that of the cord circuit C and the operators receiver will receive an impulse 'of current which produces the usual busy click in the head receiver of the operators set. This impulse'of current extends from the'tip of the calling plug CP thru normal contact 23 of the relay LD, conductor 24, alternate contact 19 ofthe listeningrelayLS, conductor 7 25 to ground through the tertiary winding of the operators induction coil. This impulse of current produces a click in the operators head receiver in the well known man-:

ner. Assuming that the line is idle'the opera v tor inserts the calling plug CP into the jack J of the wanted line closing a series energizing circuit for the link disconnect relay LD and the cut off relay CO-- of the line circuit L associated with the called line B traced from battery through thewind ings 26 and 27 of the relay LD, conductor 28, normal contact 29 otthe relay LDC, con.-

ductor 30, sleeve contact-s of the connected plug CP and iack J to groundthrough the cut ofl' relay CO. The closing of alternate contact 31 establishes a circuit for the relay LD' from battery through the low resistance winding 26 of the relay LD', it-salternate contact 31 to ground through the winding of the cut off relay'CO, over the path just described, and this circuit just traced shunts out the high resistance winding 27 of the relay LD permittingrelay CO to operate The opening of normal Contact 17 of-the relay LD opens' the energizing circuit of the listening relay LS and the relayLS upon deenergizing opens itsalternatecontacts 18, 19 and 20 to disconnect the operators set 0 from the-cord conductors. The closing of alternate contact 17 of relay LD also establishes a circuit for the calling-swpervisory lamp CL, from battery through the lamp- CL, normal contact 32 of the relay LDC, conductor 33, normal contact 34.0f theringing control relay RCR, conductor 35, normal contact 36 of the calling supervisory relay CS, conductor 37, normal contact 38 of the relay LDC, conductors 39 and 40 to ground at alternate contact 17 of the relay LD. The calling supervisory lamp signal CL is lighted over this circuit and remains lighted until the operator depresses the party line ringing key RK. Having inserted the calling plug CP in the jack J of the called line the operator now depresses the proper ringing key plunger of the party line ringing key RK to a fully depressed position to close the end spring contacts 41 and 42 and to connectthe proper ringing generator'G, G, (St or Gr to signal the called for. subscriber at substation Ba The closing'of alternate contact 41 of the end springs of the ringing key RK closes van energizing circuit for the relay RCR tablish a locking circuit for itself, traced -from battery through the winding of the relay RCR, its alternate contact 34, conductor 35', normal contact 36 of relay CS, conductor 37 ,normal contact 38 'otrelay LDC, conductors 39 and 40 to ground at alternate contact 17 of the relay LD. Therelay RCR upon energization opens its normal contact 34 to open the circuit of the calling superv visory lamp CL which iseffaced and gives subscriber at substation B is signalled; 'After the (ringing key plunger ot'rthe ring- The relay RCR cnerthe operator an indication that the called, '7

ing key RK associated with the selected ring- W ing'frequency is released it assuines its-indicating position which allows the end' spring contacts 41 -and 42 to assume their normal position, but'as the relay RCR is locked to ground at alternate contact 17 of I the relay LD" as just described, the ringing interrupter relay RI'is now connected to the constantly rotating interrupter, I; traced from battery through the winding of relay RI, alternatejcontact 45 of relay RCR, conductor 46, normal/contact 42 of the end springs to ground throughthe constantly rotating interrupter IQ Ringing f currentfrom the generator Cr which we will assume is the ringing frequency selected is now traced from the'generatorG,-alternate contact 50 of the ringing key plungeiyconductors 51 and 52, normal contact 53 of the reversing key RV, conductor .54, alternate contact .55 of the ringing interrupter relay RI, conduct-or 56, alternate contact 23 oft-he relayLD, tip contacts of the connected plug CP and jack J, through the condenser and call ,bell at the called substation B, backthrough the ring contacts of the connected jack Jtandplug CP, alternate contact 57 of .the relay LD,;conductor'58,

alternate contact 59 oii relay RI, conductor 60, to groundat normal contact 61 of the reversing key RV. The relay BI is interlnitten-tly energized and 'deenergized by the interrupter I and the ringing current from the generator G is thus applied to intermittently substation B is being signalled.

.at the substation A.

operate the call signal at the called substation B. The closing oi alternate contact 62 of relay RI transmits aringing tone to the calling subscriber at the substation A which is traced from the generator Gi'over conductor (59 through the condenser and resistance 71 through alternate contact 62 ot the relay RI and over conductor 72 to the tip conductor of the cord C and to the calling substation A. This gives the calling subscriber at the substation A an audible signal notifying him thatthe called subscriber at The called subscriber at substationli is thus automath cally signalled over the ringing circuit just traced until he answers in response to his call signal or until the calling subscriber at the substation A replaces his receiver before the called SljlbSCllbQl' answers.

Should the calling subscriber at the substation A replace his receiver upon the switchhook:before the called subscriber answers, the supervisory relay AS will restore due to the interrupted switchhooh' contacts The relay AS upon deenergization closes its normal contact 73 which establishes an energizing circuit for the link disconnect control relay LDC traced from battery lll'llOLlgl'l the winding of the relay LDC, conductors 7A and 75, normal contact 73 oi? relay AS, conductor 76, alternate contact 77 ot the relay LD conductor 40 to ground at alternate contactcl'i of the relay Ll). The relay CR is also energized upon the closure of normal contact 73' over a circuit traced from battery through its upper windingTS, conductors 74; and 75 to ground at alternate contact 17 of relay LD over the path just traced for relay LDC. The relay LDC upon energization opens its normal contacts 5 and 29 which open the energizing circuits of the relays LD and LD, said relays restoring to normal. The opening of normal contact 38 of the relay LDC opens the locking circuit for the ringing control relay RCR and the relay deenergizes to open its alternate contact 45, which opens the circuit of the ringing interrupter relay RI and the relay RI restoring to normal, its alternate contact 55 is opened to disconnect the generator G and prevent further application oi. ringing current to the called subscribefis line. I

The closing of alternate contact of the relay LDC establishes an energizing circuit for the auxiliary sleeve relay AU, traced from battery through the winding of the relay AU, conductor 81, alternate contact 80 oi. the relay LDC, conductor .30, sleeve contacts of the connected plug CP of jack 3 to ground through cut oil relay C0 of the line circuit L. The relay LDC has its initial energizing circuit opened at alternate contact 17 of relay LD' when the same deenergizes but the closing of alternate contact 82 of the relay AU 'establishes a substitute circuit for the relay LDC traced from battery through the winding of the relay LDC, its, alternate contact 38, conductors 89 and 4:0 to ground cuit forthe answering supervisory lamp AL traced from battery through the lamp AL,

alternate contact 83 of relay CR conductors- 84 and 16 to ground at normal "contact 17 ot the relay LD and the closing of alternate contact 32 of the relay LDC establishes a cir-- cuit :lor thecalling supervisory lamp CL, traced from battery through the lamp CL, alternate contact 32, conductors 8A and 16 to ground at normal contact 17 of the relay LDC The two lighted supervisory signals CL and AL are now lighted and indicate to the operator of the cord C that the calling subscriber at substation A has replaced his receiver.

The opening of alternate contacts 8 and 9 of the-relay LD disconnects the cord conductors from the calling line and the opening of normal contact 5 of the relay LDC opens the energizing circuit of the cut oli' relay CC allowing the relay to restore which permits the calling subscriber at substation A to immediately recall so that upon the removal of the receiver at substation A the line relay LR will again energize to permit the lighting oi? the line signals S. The opening of alternate contacts 23 and 57 ot the relay Ll) disconnects the calling end of the cord conductors from the called line and as the relay AU is now in series circuit Withthe cut oil relay CO in place of the relay. LD which was disconnected when the normal contact 29 of relay LDC was openedfthe cut oil relay CO deenergizes due to the high resistance of the relay AU to again place the line relay LR of the line circuit L under the control of the called subscriber at the substation B so that should the subscriber at the called substation B remove his receiver the line relay LR will energize to light the line signals S.

Returning now to the point where the call bell at the called station B is intermittently rung, the subscriber at the called substation B in response to his call signal removes his receiver from the switchhook. When the relay RI is in a deenergized condition which is during a silent period the calling supervisory relay CS Will operate over a circuit traced from battery through the lower Winding oi the relay CS, conductor 90, normal contact 59 of relay RI, conductor 58, alternate contact57 of the relay LD, ring contacts of the connected plug CP and ack J", through the now closed contacts of the substation switchhooln back through the tip llb It'l

l in

contacts of theconnected jack :J, and plug CP, alternate contact23 ofthe relayLD,

conductor 56, normal contact of the'relay RI, conductor QOto ground through the upper Winding-of the relay CS. The relay CS upon energizing opens its normal contact 36 which opens the locking circuit-of thezringing. control relay RCR, and the ringing con trol relay RCR upon deenergization opens its alternate contact 45 which disconnects the ringing interrupter I from the rclayvR-I The relay BI is prevented ii'romjenergizing and remains at normal thus preventing the further application of ringing current. to the called subscribers 11116, q

The closing of alternate contact'36 of the switchhooks. The replacing of the receiver at the substation A allows the relay AS to restore to normal due to the interruptionwof its energizing circuit at the switchhook contacts. V The closing of normal contact 73 of the relay AS establishes an energizing circuit for the link disconnect cont-rol relay LDC traced from battery through the Winding of the relay LDC, conductors T4 and 75,

normal contact 7 3 ofthe relay iAS, conduc-. tor 76, alternate contact 77 of the relay LD, conductor 40vto ground atalternate contact 17 of the relay LD and the relay LDC upon energizing opens its normal contact 5 Which opens the energizing circuit of the linkdisconnect relay LD. The relay LD upon der. energization restores to normal and the openingof alternate contacts 8 and 9 -disconnects the cord conductors ofthe cord C, from the jack J and the relay CO of the line circuit L also restores to normal due to the; opening or" normal contact 5 of relay LDC.

The relay CO upon deenergization again places the line relay LR of the link circuit L under the control of the calling subscriberat the substation A- so that if he Wishes to recall, the removal of the receiverat the substation :again causesthe energization of the line relay LR which relay LR again brings about the lighting of the line sig- Relay LDC upon energization opens its normal contact 29 to open the initial ener gizin'g circuit of the l nk disconnect relay LD, butthe relay LD is -held energized over-a-circuittraced from battery through the Windingj26 of the relay LD, its alternate contact 31, conductors 28 and 93,- alternate contact 94.01 relay CS conductors 95 and 30, SlGGVQiCQIltfiCtS of the connected plug CI: andjack J to groundthrough thecu't ofi' relay CO. jThe closing of alternate con tact 80jof theli'elay LDC establishes an energizmg circuit for-the relay -AU traced from battery through-the Winding oft-he relay AU,

conductor 81', alternatecontact 80 of the relav LDC conductor 30, sleeve contacts of the plug. CP- and jack J 7 to ground through the a Y i cut oil relay CO and the relay All is ener-v gized in parallel with the link disconnect 17elay LD overthe circuit just traced. The

relay LD upon deenergization opens its alteri nate contact 77 which opens the initial ener 'gizing circuit of the relay LDC, but thereilay LDC is held energized over a circuit traced from battery through the Winding of the relayLDC its alternate contact 38, conductors 39 and 40 to ground at alternate contact 82 of the relay AU. .The opening 7 of normal contact 38 of the relay LDC also opensv the initial energizing circuit for the relayCR'but the relay CR is held energized over a substitute circuit which may be traced from battery through its upper Winding 78, conductor 74, alternate contact. 38 of relay LDC, conductor-s39 and 40 to ground at alternate contact 82 of the relay'AU. v

When the called subscriber, at substation B replaces his receiverupon the switchhook the circuit of the calling supervisory relay CS is interrupted at the switchhook contacts and the relay CS uponv restoring opensits alternate contact '94 which allows the relay LD to restore to normal and the opening of its alternate contacts 28 and 57 opens the tip and ring conductors of the cord-C. The

closing of normal contact 17 now closesa circuit for the answering supervisory lamp AL and the call ng supervlsory lamp CL, the

circuit .for the supervisory lamp CL being traced from battery through the lamp CL,

alternate contact 32 of relay LDC, conductors 84 and 16 to ground at normal contact 17,,of the relay LD, and the circuit for the answering supervisory lamp AL istraced from, battery through the lamp AL alternate contact 83 otrelay CR, co'nductors84t and 16 to ground at normal contact 17 ofre- The relay AU remains connected in series circuit With the cut off relayCO, afterthe relay LD is deenergized due to the high resistance of relay AU the relay CO" deener'-' gizes and again places the line relay LR under the control of the called subscriber at substation B and should the subscriber at substation initiate a recall, theremoval of the receiver at substation B will close an energizing circuit for the linerelay LR to again light the multiple line'signals S. The

answering plug AP disconnects the cord C from the jack J and the withdrawal of the plug CP from the jack J brings about the deenergization of the relay AU, and the relay AU deenergizing, opens its alternate contact 82 to openthe energizing circuits of the I relays LDC and CR. The opening of alternate contact 32 of the relay LDC e'fiaces the calling supervisory signal CL and the opening of alternate contact 83 of relay CR ettaces the answering superivsory signal AL and the apparatus used in establishing a connection between the calling substation at substation A and the called subscriber at substation B is now at normal and available for use in establishing other connections.

Assuming that the called subscriber at substation B is the first toreplace his receiver, the replacement opens the energizing circuit for the relay CS at the switchhook contacts and the relay CS restores to normal. The closing of normal contact 36 ot' the relay CS closes a circuit for the calling supervisory lamp CL traced "from battery through the lamp CL, normal contact 32 of relay LDC, conductor 33, normal contact 34 of relay RCR, conductor 35, normal contact 36 of relay CS, conductor 37, normal contact 38 of relay LDC, conductors 39 and 40 to ground at alternate contact 17 of relay LD and the signal CL is thus lighted over this circuit. The opening of alternate contact 36 of the relay CS also opens the energizihg circuit for the relay CE. The called subscriber replacing his receiver does not affect the link disconnect relay LD associated with the, calling end of the cord C as the relay LD is held up through normally closed contacts of the relay LDC and should the called subscriber wish to recall before the calling subscriber has replaced his receiver, the supervisory relay CS will be under the control of the switchhook contacts and the movement of the switchhook at the called substation will cause the relay CS to energize and deenergize to flash the calling supervisory signal CL. Now when the calling subscriber at A replaces his receiver the opening of the switchhook contacts brings about the deenergization ot' the answering supervisory relay AS and the closing of its normal contact 73 brings about the energization of the relay LDC and the operation of the apparatus to effect disconnection is the same as previously described.

1 Assuming now that the subscriber at the substation A initiated a call the removal of the receiver thereat energizes the line relay LR which relay LR upon energization causes the line signals S to light. The operator associated with the cord circuit C seizes the call to the exclusion of other operators as before described by inserting the answering plug AP into the ack J of the calling line to bring about the operation of the cut oil relay C0 of the line circuit L and p prising substations A, A, A and A and upon inquiry of the operator the subscriber at substation A informs the operator that he wishes to converse with the subscriber A The operator is immediately aware of the fact that the party wanted is on the same line with the'calling subscriber at A due to the fact that the answering plug AP is already inserted in the jacket the party line into which subscribers A and A terminate. The operator now asks the: calling party at the substation A to replace his receiver and then withdraws the answering plug AP from the jack J of the party line and inserts-the calling plug Cl of the cord circuit C in the jack J. ,The withdrawal of plu AP allows relays CO, LD, AS-aml L5 to restore.

The insertion of the plug CP into the jack J ot'the party line to which both the calling and called parties are connected brings about the energization of the link disconnect relay LD, traced from battery through the windings 26 and 27 ot' the relay LD"; conductor 28,'normal contact 29 of relay LDC, conductor 30, sleeve contacts of the connected pltw CP and jack J to ground throughthe windlng of the cut oil relay C0.

lUf)

The relay LD upon energizing closes its alternate contact 31 and closes a locking circuit tor itself which extends from battery ill through its winding 26. its alternate contact gized over this circuit. The relay LD upon energizing closes its alternate contact 17 to light the calling supervisory lamp CL over a circuit as previously described and the lamp CL remains lighted until the operator depressesthe partyline ringing key RK to signal the called for substation A V The operator now depresses the proper ringing key plunger of the party line ringing key BK to its fully depressed position to close the end spring contacts 41 and 42 and to connect the proper ringinggenerator G, G, G or G to signal the called for subscriber at the substation A The closing of the end spring 41' closes an energizing 17 of relay LD.

circuit for the ringing control relaywRCR,

RI traced from battery through the winding of relay RI, alternate contact 45 of relay RCR, conductor 46,130 ground at alternate contact 42 of the end springs. RCR upon energizing closes its alternate contact 34 establishing a locking circuit for itself traced from battery through its winding, its alternate contact 34, conductor 35, normal contact 36 ofrelayCS, conductor37, normal contact 38 of relay LDC,'conductors 39 and 40 to ground at alternate contact WVhen the operator releases the ringing key plunger it assumesits ringing or indicating position to allow the end springs to restore to norm-ah and the closing of normal contact 42 of the end springs now connects the constantly rotating interrupter I'in circuit with the relay R1 to intermittently energize the same. The clos- 1 ing' ofalternate contact of the relay RI connects ringing current from the generator G which we will assume is the generator selected to ringthe call bellfof thesubscriber at substation A Ringingcurrent fron the generator G is thus transmitted to the called substation A to intermittently signal the called substation A due to the energization and deenergization of relay RI under the influence of the constantly rotating interrupter I, and the ringing current from the generator G traverses a path as previously described.

The subscriber at the substation A in response to his call signal removeshis' re ceiver fromthe switchhook which closes an energizing circuit for the calling super visory relay CS through normal contacts 55 and 59 of relay RI when in a deenergized condition and the now closed contacts at the switchhook at substationA? The relay CS upon energizing opens its normalcontact 36 I which opens the locking circuit iof relay RCR which relay upon deenergizing-opens its alternate contact 45 to open the energizing circuit of. the relay RI- which pre vents further application of ringing'current to the called substation A The closing of alternate contact- 36 of relay.CS closes an energizing circuit for relay CR tracedfrom battery through the lower winding 91 of relay CR, conductor 92, alternate contact 36 of relay CS, conductor 37, normal con tact 38 of relay LDC,- conductors 89' and 40 to ground at alternate contact 17- of relay LD. circuit and the closing of its alternate con- The relay The relay CR is energized over this tact 100 closes-a circuit forthe relay LDC traced fronrbattery through the Winding of I relay LDC, conductors. 74'- and 75, normal 7 contact/73M relay A S, conductor 101, alternate contact 100 of relay CR, conductors 102 and 40 to ground at alternate contact 17 of relay L1). The relay LDC upon energizing opens its normal contact 29 to open the initial energizmg circuit of the relay LDybuta substitute circuit is established tor the "relavLD traced from'battery through its winding 26, its alternate contact 31, conductors 28 and 93 alternate contact 94 of relay CS, conductors'95 and 30, sleeve con-- ,tac-ts of the plug CP and jack J to ground through the cut .ofi' relay-CO. -The -relay LDC upon energizing closes its, alternate contact 38 to establish a locking circuit for itself from battery throughthe winding of relay LDC, its alternate contact 38yconductors 39 and 40 to ground at alternate'colr tact 1'7 .of'relay LD. The closure ofalters nate contact 38 of relay LDC also, closes a circuit through the upper winding of relay CR- traced frorn battery through. the windingflTS of relay CR, conductor 74, alternate contact 38, conductors '39 and 40, to ground atalternate contact 17. Thefclosing of alternatecontact of relay LDCcloses a circuit for the relay AU'traced from battery through the winding of relay AU, conductor 81 alternate contact 80 of relay LDC, conently be described. 1 a

' Thecalling subscriber at thesubstation A i removes his receiverindue time and the i called subscriber at the substation A on this same linc and the subscriber at the calling substation A are now in conversational circuitfi The subscribers having finished their conversation replace their receivers upon the switchhooks which causes the relay C8 to restore. Therelay' CS deenergizing its alternate contact 94 isl restored which opens the, circuit forthe relayLDavhich restores openingits alternatecontacts 23, 31, 17 and 57. Theflocking circuit for relay LDC is openedat alternate contact 17 of relay LDv as is'a'lso the circuit through the upper winding 7 8 of relay CR but relayLDC and relay CR are maintained energized over a substitute circuit over conductors 39 and 40 to ground at alternate contacts 82 of relay AU. The relay LDC remaining energized,

moval of the receivers at 'anyof the stationson the party line will operate the line relay LE to light the line signals S. When the subscribers replaced their receivers the calling and :alled supervisory lamps AL and UL were lighted through alternatecontacts 32 of relay LDC and 83 ot relay CR to ground at normal contact l? of relay LI) and the operatorobserving the two lighted signals AL andv CL withdraws the calling plug Cl from the jack J which opens the circuit of rclay AU and the opening of al ternato "contact 82 ot relay AU opens the circuits for relays LDC and CR. paratus is now at normal and available for establishing other connections.

While I have descrlbed my invention operating in connection with a certain circuit arrangement, I do not wish to be limited to the same as changes and modifications may readily sijig'gest themselves to those skilled in the art, and I theretore aim to cover all such changes and modifications as come within the spirit and scope of the appended claims;

Having described my invention what 1 claim is new and desire to secure by United States Letters Patent is:

1. A telephone system having party lines each provided with a pluralityot answering jacks and line signals terminating at a plurality of operators positions, link circuits provided with connection tern'iinals for interconnecting said lines, a calling subscriber andva called subscriber on one of said party lines connected in conversational circuit via one of said link circuits, and means in said link circuit including a disconnect relay energized upon the connection ot one of said terminals to the party line and a supervisory relay controlled over said subscribers telephone line for deenergizing said disconnect relay thereby disconnecting said linkcircuit from the jack of said party line;

2. A telephone system having party lines each provided. with a plurality of answering jacks and line signals terminating at a pinrality ofoperators positions, link circuits provided with connection terminals for interconnecting said lines, a calling subscriber and a called subscril'ier on one of said party provided with answering and calling plug The apo. A telephone system having party lines terminals for interconnecting said lines, a calling subscriber and a called subscriber on one of said party lines connected for conversation by said calling plug terminal of one otsaid link circuits with the jack of said party line, and means in said link circuit controlled by said subscribers telephones for disassociatii'ig said link circuit from said party line and supervisory sig nals for said link circuit controlled by said subscriberstelephonesvon said party line.

Y a-. A telephone system having party lines each provided with a plurality of answering jacks and line signals appearing at a plurality of operators positions, link circuits provided with answering and calling plug terminals tor interconnecting said lines, a calling subscriber and a called subscriber on one of said party lines connected for conversation by the calling plug of one of said link circuits, a link disconnect relay for said cord energized upon the connection of said calling plug with the jack of said party line, and m ans including a supervisory relay in said connected cord for controlling the deenergL Zation of said link disconnect relay to disassociate said connected cord from the jack of said party line.

A telephone system having party lines each provided with a plurality of answering jacks and line signals appearing at a plurality of operators positions, link circuits providod with answering and calling terminals, a calling and a called subscriber on one of said party lines connected for conversation by the calling terminal of one of said link circuits with a jack of said party line, a link disconnect relay for said link circuit energized upon connection of said link circuit with the jack of said party line, a supervisory relay for said cord controlled by said subscribers telephones and a second relay caused to be energized by said supervisory relay, said second relay controlling means in said connected link circuit operable upon termination of conversation of said subscribers to deenergize said link disconnect relay to disassociate said link circuit from said jack of the connected party line.

6. A telephone system having party lines each provided with a'plurality of jacks and line signals appearing at a plurality of operators positions, link circuits provided with answering and calling plug terminals for connecting said lines, a calling and a called subscriber on one of said party lines connected for conversation by a calling plug terminal of one of' said link circuits with a jack of said party line a link disconnect relav for said cord energized by'thc connection of said calling terminal with the party line, subscribers controlled means adapted to deenergize said link disconnect relay for disassociating said link circuit from said party line and a second relayifor said cord affected by said subscriber controlled means to render said partyline available for connection.

7. A'telephone systemhaving party lines each provided-with a pluralityof jacks and line signals appearing at a plurality of operators positions, link circuits providedw-ith answering and calling plug terminals forinterconnecting said lines, a'calling and a called subscriber on one of saidparty lines connected for conversation by the engagement of the calling terminal of'one of said link circuits with a jack of said party line, a link disconnect relay for said cord energized upon connection of said link circuit with said party line, a supervisory relay for said cord controlled by said subscribers telephones, a second relay energized by said supervisory relay vfor controlling means in said link circuit operable upon termination of conversation of said subscribers to deenergize said link disconnect relay to disassociate said linkcircuit from saidjack of the connected party line, a relay associated with said means adapted to render said party line available for connection or recall, and supervisory signals for said link circuit controlled over said subscribers line.

'8. A telephone system including a subscribers polystation telephone line, a link circuit for connection thereto when substations on said line are to be included in conversational circuit, subscriber controlled means controlled over said line for freeing said line from said link'circuit, and supervisory signal in said link circuit controlled over said line for indicating'the condition of said link circuit. 7 v a 9. A telephone system including a subscribers polystation telephone line, a link circuit for connection thereto when substations on said line are to be included-in conversational circuit, subscriber controlled means controlled'over said line for freeing said line from said link circuit so that the subscribers on said line may recall before the link circuit is returned to normal, and

supervisory signals for saidlink circuit controlled over said subscribers line for indicating the condition of said link circuit.

10. A telephone system including a subscribers polystat'ion line having multiple MICHAEL B. STAZAK. 

